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<title>malloc</title>
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<h2 align=center>malloc</h2>
<h4 align=center>OS/161 Reference Manual</h4>

<h3>Name</h3>
<p>
malloc - allocate memory
</p>

<h3>Library</h3>
<p>
Standard C Library (libc, -lc)
</p>

<h3>Synopsis</h3>
<p>
<tt>#include &lt;stdlib.h&gt;</tt><br>
<br>
<tt>void *</tt><br>
<tt>malloc(size_t </tt><em>size</em><tt>);</tt>
</p>

<h3>Description</h3>
<p>
<tt>malloc</tt> allocates <em>size</em> bytes of memory and returns a
pointer to it. The memory is not necessarily zero-filled. (To get
zero-filled memory, call <A HREF=bzero.html>bzero</A> or
<A HREF=memset.html>memset</A>, or use
<A HREF=calloc.html>calloc</A>.)
</p>

<p>
The pointer returned must be suitably aligned for use with any data
type.
</p>

<p>
When asked to allocate zero bytes, <tt>malloc</tt> may either always
return <tt>NULL</tt>, or may return distinct non-null pointers that do
not point to any storage.
</p>

<p>
While <tt>malloc</tt> may at its option allocate more than
<em>size</em> bytes to fill a request, code that calls <tt>malloc</tt>
may not depend on such behavior and must not perform any accesses
outside of the bounds defined by <em>size</em>.
</p>

<p>
It is legitimate for memory returned by malloc to not actually be
physically mapped until it is used.
If at the time it is used, no physical memory is available and there
is no space to swap something out to make room, the process may
potentially receive a fatal signal or be killed.
This behavior is often somewhat contentious; a full discussion of the
possible alternatives and their pros and cons is well beyond the scope
of this man page.
</p>

<h3>Return Values</h3>
<p>
<tt>malloc</tt> returns a pointer to the memory allocated. If memory
cannot be obtained, NULL is returned.
</p>

<h3>See Also</h3>
<p>
<A HREF=calloc.html>calloc</A>,
<A HREF=realloc.html>realloc</A>,
<A HREF=free.html>free</A>
</p>

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